Factors affecting osmosis:
- Temperature: At constant pressure, the water molecules move from their higher concentration to lower concentration.
- Pressure: At constant temperature, the water molecules move from their higher concentration to lower concentration.
- Solute molecules: As the difference between two solution increase , the rate of osmosis also increase.
Significance of osmosis:
a) Plant roots absorb water by the process of osmosis.
b) Osmosis help in cell to cell movement of water.
c)Osmosis help growth of the tissue.
d) It help in opening and closing of stomata.
e) Turgidity of a cell resulting from osmosis maintain the shape of organ and makes the organ rigid.
Plasmolysis:
The shrinkage of protoplasm of plant cell due to the loss of water when placed in hypertonic solution is called Plasmolysis.
Deplasmolysis:
If we place the plasmolysed cell in a hypotonic solution, the water enters inside the cell and cell become turgid. This is called deplasmolysis.
Significance of plasmolysis
a) Plasmolysis is character of living cell, dead cell can’t show plasmolysis.
b) It indicates the semi-permeability nature of the plasma.
c) It is used to determine the osmotic pressure of the cell sac.
d) It also help in food preservation.
e) It checks the growth of bacteria and fungi in jams and jellys, as bacteria and fungal cell are plasmolysed in concentrated sugar solution.
Imbibition
The process of increase in the volume of a solid by soaking in water is called imbibition. Eg: Swelling of doors and windows, swelling of gums, resins, etc. Cellulose , pectic substance, protoplasmic proteins and other organic compounds in plant cell show imbibition.
Significance of imbibition
a) It help in germination of seeds because the stored food or seed swells causing the seed coat to rapture.
b) Before absorption of water in root cause imbibition.
c) Brusting of pollen grains or pollen tubes inside the ovary is due to imbibition.